This invention relates to medical intravascular devices such as catheters for withdrawing or injecting a substance from or into a patient's vein or other channel or canal of the patient's body.
Such catheters typically comprise an elongated thin tubular member having a sharp pointed end for piercing the skin and introducing the elongated thin tubular body of the device far enough into the vein, or other internal body canal, to enable the withdrawal or injection to proceed. The tubular members of some older prior art catheters are of metal, which has the disadvantage of piercing or otherwise injuring the inner wall of the vein or other body cavity or canal in which it is inserted since the metal is stiff and does not follow the turns and bends of the vein or other body cavity or canal. To overcome this disadvantage, thin outer tubular members or cannulas of flexible plastic were provided to sheath the thin metal tubular member or stylet. The sharp pointed end of the stylet would pierce the skin and introduce the device into the vein, after which the metal stylet would be withdrawn while the flexible plastic sheath or cannula would be inserted a desired further distance into the patient's vein or other bodily portion. However, it has been found that significantly more cases of infection result at the entrance region of the body when the tissue contacting portion of the device is made of such plastic material. The present invention significantly reduces the risk of infection by coating the plastic devices with metal throughout, or at the region which is in contact with the patient's tissue at the entrance point of the device into the skin, or otherwise providing a metal contacting surface at such region.